Shifting devices for transmitting shaft commands to the transmission of a motor vehicle, in which the movement of the selector lever can be blocked by a device, are generally known.
Thus, the selector lever of an automatic transmission is frequently provided in these prior-art shifting devices with a locking device, which permits shiftings into another position only after a pushbutton has been depressed in the shift knob. A locking bar is guided here mainly in the interior of the gearshift lever. It is actuated by the pushbutton and engages a shifting gate with a corresponding locking contour. For example, shifting from the shift position P (park) into the shift position R (reverse) and from R to P and N (neutral) after R may be possible only after depressing the pushbutton. One US standard requires a so-called keylock system. According to this standard, two requirements must be met. On the one hand, the selector lever cannot be shifted out of the shift position P with the ignition key removed, and, on the other hand, the ignition key must not be removed when the selector lever is not in the shift position P.
To meet these requirements, the locking mechanism is frequently connected to the ignition lock via a bowden cable. The bowden cable is coupled with the locking mechanism via a mechanism. If the ignition is not turned on, the bowden cable is blocked by the ignition lock, and the locking mechanism is thus in its blocked position as well. Shifting out of P is prevented. If the ignition is turned on and the selector lever is shifted out of position P, the locking bar and the mechanism pull on the bowden cable, as a result of which a mechanism in the ignition lock ensures that the ignition key cannot be removed. The bowden cable is pulled into its blocking end position in the ignition lock either only by depressing the pushbutton in the shift knob or, on the one hand, by depressing the pushbutton and, on the other hand, by a shifting movement of the selector lever during the shifting out of P. However, the bowden cable must have reached its end position in position R at the latest. It must thereafter be ensured that the bowden cable always remains in the pulled position outside position P. This is usually achieved in two different ways.
According to one solution, a locking lever is mounted in the shifting mechanism. This locking lever has two lever arms. One arm of the lever, also called a locking arm, is in contact with a corresponding opposite contour of the locking bar, while the other arm, called mostly the pulling arm, is connected with the bowden cable. If the bowden cable is now blocked, the locking bar cannot move the locking lever, and the selector lever is thus blocked as well. If the ignition is now turned on and the bowden cable is released, the locking bar is moved by depressing the pushbutton in the knob, and the locking bar will in turn move the locking lever, so that the bowden cable is pulled. To keep the locking lever and consequently the bowden cable in this position, the locking arm has an extension, or the locking lever has an additional arm, whose contour ensures by means of a corresponding opposite contour at the selector lever that the locking lever remains outside P in all shift positions in the pulled position of the bowden cable.
The second prior-art possibility of ensuring that the bowden cable always remains in the pulled position outside the position P is embodied with a locking lever that functions as described above. However, this locking lever has no extension with a corresponding opposite contour at the selector lever. The locking lever is held in the pulled position of the bowden cable by means of a spring-loaded support lever, which pivots automatically into the holding position and is pushed away by the selector lever when the selector lever is pivoted back into position P.
The drawback to the first solution is that a locking lever with an extension and with a corresponding opposite contour frequently cannot be accommodated at the selector lever for kinematic reasons or because of the limited space available. Another problem can be seen in an automatic transmission with an additional manual shift gate (Tiptronic transmission). The selector lever is moved here from position D into a second, parallel gate. The opposite contour at the selector lever must extend now not only in the direction of the automatic gate, but it must also be extended at right angles thereto. This represents an additional problem in terms of the space available.
One drawback to the second solution is that it cannot be ensured that the support lever will indeed also pivot into the holding position, because the pivoting into the holding position is brought about only by the pretension of the spring rather than by a restricted guidance.